This application relates to infrared heaters, and in particular to a new and improved heating element which may be incorporated in a portable heater or in a heating unit, a plurality of which may be physically and electrically connected to construct a bank of heaters.
Infrared dryers have been used for a multiplicity of purposes, such as baking, curing, shrink wrapping, etc. To increase the efficiency of infrared dryers and heaters, the heating elements employed in the dryers or heaters were made generally flat. The heating elements used in such dryers or heaters generally include a woven fiberglass cloth or paper (which forms the heating face of the element), an insulating blanket, and a heating element sandwiched between the fiberglass cloth and the insulating blanket. None of these materials has much structural rigidity--that is, they are all quite flexible, as provided. To impart structural rigidity to the heating element, the insulating blanket was soaked in a rigidizing solution, such as a colloidal silica. The fiberglass cloth may also have been rigidized with the solution. As can be appreciated, prior to being soaked in the rigidizing solution, the insulating blanket was "fluffy," had a high void factor, and hence, had good insulating qualities. However, once the blanket is rigidized, the blanket looses its fluffiness and a large percentage of the voids within the blanket. Thus, the blanket looses a significant amount of its insulating qualities in the rigidizing step.
As noted above, such heating elements have been used for drying, baking etc. One area where infrared dryers have been used is in the printing industry, where designs are applied to textiles via screen printing. The heaters that are presently used can be improved upon to make them easier to use. For example, the heaters can be made more flexible with respect to the height of the heating element and the ability to easily locate the heating element at a desired location relative to the textile.
Another area where such heaters are employed is in the painting industry (for example the car painting industry) where heaters are used to dry or bake paint. In an installation where a large item, such as a car, has been painted and the paint needs to be dried or cured, typically, a large number of heating elements are required to apply heat evenly over the entire surface of the painted item. This typically requires a wall of heaters. The available heaters for such uses are not easily assembled together, either physically or electrically. Such a wall of heaters therefore is difficult to assemble. Once such a wall of heaters is assembled, the individual heaters are difficult to control. Therefore, it is difficult to achieve a uniform heat distribution from the bank of heaters.